A study led by researchers at the Johns Hopkins University School of Medicine found that dopamine, a brain chemical associated with pleasure and motivation, increased the body’s need for work, particularly in people with Parkinson’s disease, characterized by: have been suggested to play an important role in how people perceive the amount of physical effort. dopamine deficiency.
Dopamine, a neurotransmitter traditionally linked to pleasure, motivation and reward-seeking, can also make physical activity “easy” for some people, according to a new study led by researchers at the Johns Hopkins University School of Medicine. It indicates what seems to be the key factor in determining why it is felt, and has been proven to be so. expend for others. This conclusion was drawn from a study of Parkinson’s disease patients characterized by progressive loss of dopamine-producing cells in the brain.
This recently published study npj Parkinson’s disease, may pave the way for the development of improved methods to encourage individuals to adopt and maintain exercise habits. In addition, the researchers say, it could lead to new treatments for fatigue associated with depression and a variety of other conditions, and could even improve our understanding of Parkinson’s disease.
“Researchers have been trying to understand why some people find physical exertion easier than others,” said study leader and associate professor of biomedical engineering at the Johns Hopkins University School of Medicine. says Dr. Vikram Chiv, a research fellow at the National Academy of Sciences. Kennedy Krieger Institute. “The results of this study suggest that the amount of dopamine available in the brain is an important factor.”
After engaging in physical activity, people’s perceptions and self-reports of effort expended vary, which influences decisions about whether to exercise in the future, Chiv explains. Previous studies have shown that people with increased dopamine are more motivated to perform physical effort for reward, but the current study shows that people with increased dopamine are more willing to perform the physical effort required for the physical task, without the promise of reward. focus on the role of dopamine in self-evaluation of effort.
For the study, Chibb and colleagues at the Johns Hopkins University Medical Institute and the Kennedy Krieger Institute recruited 19 adults diagnosed with Parkinson’s disease. Parkinson’s disease is a condition in which dopamine-producing neurons in the brain gradually die, causing unintentional, uncontrolled movements such as tremors and fatigue. , stiffness, problems with balance and coordination.
Chiv’s lab asked 10 male and 9 female volunteers, with an average age of 67, to perform the same physical task of grasping sensor-equipped hand grips on two different days within a four-week period. . One day, the patients were asked to take their standard daily synthetic dopamine drug as usual. Another was asked not to take any medication for at least 12 hours before performing the squeeze test.
On both days, patients were first taught to grasp the grip sensor with varying levels of defined effort and then asked to report the number of units of effort grasped.
When participants were taking synthetic dopamine drugs on a regular basis, their self-assessment of effort units consumed was more accurate than when they were not taking the drug. They also had less effort variability and showed more accurate squeezes when the researchers instructed them to squeeze with different levels of effort.
In contrast, when patients were off medication, they consistently overreported their efforts, meaning that they perceived the task to be physically more difficult, and the variability between grips after the cue was less It has grown significantly.
In another experiment, patients were given a clear choice between gripping the grip sensor with relatively light force, applying no effort to flip a coin, or taking chances with a very high level of effort. rice field. These volunteers were willing to take the risk of having to put in more effort if they were on the medication than if they were not on the medication.
In a third experiment, participants were given the choice of getting a small deposit, flipping a coin and getting nothing, or a larger sum of money. There was no difference in the results between subjects taking the drug and those not taking it. According to the researchers, the results suggest that dopamine’s influence on risk-taking preferences is unique to decision-making based on physical exertion.
Taken together, these results suggest that dopamine levels are an important factor in accurately assessing the effort required for a physical task, and how much effort is likely to be put into future tasks. It suggests that it could have a bigger impact. For example, perceiving that a physical task takes a lot of effort can reduce motivation for that task.
Chibb says that better understanding of the chemistry and biology of motivation could advance how we motivate exercise and physical therapy regimens. Moreover, inefficiencies in dopamine signaling may help explain conditions such as depression and prolonged COVID-19, as well as the widespread fatigue present during cancer treatment. Currently, he and his colleagues are investigating the role of dopamine in clinical fatigue.
References: “Dopamine Facilitates the Translation of Physical Movement into Appreciation,” Purnima Padmanabhan, Agostina Casamento-Moran, Aram Kim, Anthony J. Gonzalez, Alexander Panteljat, Ryan T. Roemich, Vikram S. Chiv, 1 April 2023, Available here. npj Parkinson’s disease.
DOI: 10.1038/s41531-023-00490-4
Other researchers who participated in the study include Purnima Padmanavan of Johns Hopkins, Agostina Casamento-Moran, and Alexander Panteljat. Ryan Roemich of Johns Hopkins University and the Kennedy Krieger Institute. And Anthony Gonzales of the Kennedy Krieger Institute.
This study was funded by the Eunice Kennedy Shriver National Institute of Child Health and Human Development. National Institutes of HealthNational Institute of Mental Health, National Institute on Aging.
